Fig. 3. Vocalizations and sounds recorded in different compartments of the vocal tract. (A) Emitted vocalization and tracheal sound from the same coo. (B) Emitted vocalization and esophageal sound from the same coo, uttered by a different dove. Oscillogram (top panels), spectrogram (middle panels) and power spectrum (bottom panels) of signals recorded in different compartments of the vocal tract. The DC offset in the e2 note of the tracheal and the esophageal signals is due to the pressure increase in the respective compartments. This offset can vary from coo to coo, although it appears similar in the examples shown. Coos in A and B come from different individuals.